Methods and apparatus for laying elongate flexible means on a submerged surface



1966 F. R. HAUBER ETAL 3,280,571 METHODS AND APPARATUS FOR LAYING ELONGATE FLEXIBLE MEANS ON A SUBMERGED SURFACE Orzgmal Flled July 14, 1958 5 Sheets-Sheet 1 INVENTOR5 Oct. 25, 1966 H B ETAL 3,280,571

METHODS AND APPARAiUS FOR LAYING ELONGATE FLEXIBLE MEANS ON A SUBMERGED SURFACE Original Filed July 14, 1958 5 sheets-sheet 2 dose 0b 5. Lawrence fiend/00x70 ha uber' INVENTORS ATTOR/Vf) 3,280,571 ELONGATE FLEXIBLE 5 Sheets-Sheet 3 ETAL damp/7 .5. Lawrence f er'd/nono E. f/auber INVENTORS US FOR LAYING F. R. HAUBER METHODS AND APPARAT Oct. 25, 1966 MEANS ON A SUBMERGED SURFACE Original Filed July 14, 1958 ATTORNEY United States Patent 3 280 571 METHODS AND APPAJRATUS FOR LAYING ELON- GATE FLEXIBLE MEANS ON A SUBMERGED SURFACE Ferdinand R. Hauber and Joseph Benton Lawrence,

Houston, Tex., assignors to Brown & Root, lnc., Houston, Tex., a corporation of Texas Continuation of application Ser. No. 157,531, Dec. 6,

1961, which is a continuation of application Ser. No.

748,373, July 14, 1958. This application Apr. 30, 1965,

Ser. No. 457,239

11 Claims. (Cl. 6172.1)

This is a continuation of application Serial No. 157,531, filed December 6, 1961, now abandoned, which in turn was a continuation of application Serial No. 748,373, filed July 14, 1958 and now abandoned.

The invention pertains to the laying of pipelines in underwater ditches or on the bottom of water covered terrain. More particularly, the invention pertains to the laying of pipelines in water up to 100 feet in dept-h. This type of operation requires that the pipe beinglaid be supported through the major portion of its trip from assembly and treating to final position on the'bottom.

There are a few laborious methods, employing relatively crude devices, now in use for the above purposes. However, the ability of the known devices to lay pipe underwater is severely limited to depths greater than 25 feet.

The greatest limitation of the known devices is their inability to properly support the pipeline between the time it leaves the water craft (usually a barge) on which it is assembled and treated, until it comes to rest on the bottom. Furthermore, such support as is given by known devices is erratic and uneconomic of effort and expense.

The laying of pipelines in water up to 100 feet in depth is not economically feasible with known devices.

In convention practice, the assembled pipe slides off the rear of the barge into the water as the barge moves forward. A roller or skid member is located on the rear of the barge for the operation. Some of these barges have a hinged floating ramp attached to the rear which is equipped with the rollers or skids. The floating end of such hinged ramps is depressed by the weight to the pipe sliding thereover. Of course, such a ramp can give only a nominal amount of support to the pipe in the water at or near the surface thereof, which is limited to the unvariable buoyancy of the ramp. The portion of the pipe suspended in the water between barge ramp and the bottom is unsupported and the length of the bending radius of such portion of the pipe cannot be effectively controlled.

If the water is of more than nominal depth, the unsupported weight of the pipe in the water will often reduce the bending radius thereof to the point that great stresses are set up in the pipe and its covering, causing rupture of one or both. In the deeper water, conventional practice is to support the portions of the pipe suspended underwater by attaching pontoons with floating release lines, to the pipe at spaced intervals. However, the expense, effort, and time required, together with the generally inaccurate and unsatisfactory results obtained, make such operations not feasible in depths exceeding 50 feet.

The principal object of the invention is to provide a means for laying pipe in water more efiiciently and in greater depths than heretofore possible.

One of the principal objects of the invention is to properly support ipelines suspended underwater during laying operations.

Another object of the invention is to control the bending radius of the pipe as it is laid from a water craft in order to alleviate stresses and to prevent collapse, rupture or fatigue of pipe and cover.

Another object of the invention is to provide buoyant supporting means for the pipe suspended underwater which are not attached thereto.

Patented Oct. 25, 1966 "ice Another object of the invention is to provide means for continuous and interacting support of the pipe both above and below the surface of the water.

Another object of the invention is to provide means for remotely controlling the location and amount of buoyant support given portions of the pipeline suspended underwater during laying operations.

Another object of the invention is to provide a means for facilitating the handling of pipelines on barges whereby the assembled pipeline is protected from damage .by excessive bend-ing or twisting and the stresses imposed thereby, in the process of assembling and treating the pipe on the barge.

Briefly, the invention comprises an elongated, buoyant pipe cradle device, which is flexibly attached to the rear of a pipe laying barge, and pipe supporting and guiding elements on the barge itself. The buoyant pipe cradle comprises two elongated cylindrical pontoons assembled in a parallel position and joined by downwardly disposed U shaped tubular cross members. A comparatively short portion of the cradle nearest the barge is downwardly angularly displaced at approximately 30 degrees from the rest of the cradle. This portion of the cradle is not joined by crossmembers. This upper portion serves to horizontally space the angled cradling portions of the cradle from the barge in order to allow a longer pipe bend-ing radius while passing over the barge into the cradle portion.

The pontoons are longitudinally compartmented by transverse bulkheads. Each of the compartments are equipped to be flooded or to be blown out by compressed air. Each compartment is equipped with a novel gas operated and remotely controlled sea cock or valve.

The middle portions of the transverse crossmembers are lower than the pontoons and have angularly mounted transverse rollers thereon. The transverse members are hollow and serve as balance pipes between compartments of the opposite pontoons to obtain lateral floatational stability of the pipe cradle. The uppermost surfaces of the rollers mounted on alternate crossmembers are oppositely inclined, which tends to center as well as support the pipe passing thereover.

The supporting and guiding elements mounted on the barge comprise, raised, rockably mounted, roller equipped horizontal shoes with vertical rollers on their lateral extremities. The shoes are adjustably elevated above the barge as another means of lengthening the bending radius of the pipe passing over the barge and into the water. The shoes are usually located in tandem and spaced apart about 40 feet.

As the assembled pipe moves over the barge, it is supported and guided by the shoes. The pipe is guided and supported by the buoyant cradle at the surface and under the water. Selected parallel compartments of the cradle are equipped with an air intake line and a blowoif pipe containing remotely a controlled gas operated sea cock or valve which has a fail-safe device incorporated therein.

The amount of buoyancy and the location of the center of buoyancy of the cradle is remotely controlled at a control panel where valves in the operating or pressure lines for the sea cocks are located. These allow the remote control of the blowing out or venting and flooding of selected compartments. This is accomplished by controlling operating gas pressure transmitted to the bore of the novel operating remote control sea cocks which allows the operation of the ball check compartment of the sea cocks. A remotely controlled sea cock is located in each blow-off pipe in each compartment.

The pontoons have semi-elliptical skids on their lower ends so that the cradle can be slidably moved along the bottom if such procedure is desirable. Th flexible placement from the barge so that temporary directional instability of the barge itself need not drag portions of the pipe, already laid, out of position.

By means of the controllably variable amount of buoyancy and the controllably variable location of the center of buoyancy of the cradle, the vertical angular displacement between the sections of the pipeline on the barge, cradle, and in the water may be easily kept within desirable limits.

The most important advantage of the invention is that the assembled pipe is almost continuously supported from the point of assembly to its' permanent underwater position, thereby allowing operation in water of greater depths than heretofore possible.

Another advantage is that the lateral angular distortion of the pipe, and the stresses caused thereby, are easily controllable.

The versatility of the device, in its ability to obtain the above advantages under widely. varying conditions and depths of water, is another advantage.

Another advantage is the great saving time, effort, and expense in laying pipe in shallow water.

Another advantage of the device is its unique ability to lay pipe in depths of water up to 100 feet.

Other objects and advantages of the invention will appear from the following description of a preferred embodiment of the invention wherein:

FIGURE 1 is a schematic side view of the invention showing the invention mounted on a pipe laying barge.

FIGURE 2 is a partly elevational, partly schematic side view of a portion of the invention showing the relative positions of the upper end of the pontoon cradle, the rear of the barge and the schematic of the control headers for the gas pressure lines.

FIGURE 3 is a top view of the portions of the invention shown in FIGURE 2.

FIGURE 4 is a partly side elevational, partly schematic viewof a portion of a pontoon showing the compartmentation and the schematic location of the gas pressure line and remotely controlled sea cocks.

FIGURE 5 is a perspective view of the flexible joint between the pipe pontoons and the barge.

FIGURE 6 is a vertical sectional view of the novel, remote control sea cock used in each compartment.

FIGURE 7 is a partly cross sectional, partly elevational view of the buoyant pipe cradle taken at line 77 of FIGURE 3 showing the crossmember and pipe supporting and guiding rollers.

Referring now to FIGURES 1, 2 and 3, ramp 10 is mounted on a barge, float or ship 12 which is processing and laying pipe 11. Rockable shoes 14 in any number necessary are mounted in tandem on vertical adjustable swivel pedestals 16 on ramp 10. Horizontal rollers 17 and vertical guide rollers 18 comprise the upper elements of shoe 14. Pontoons 20 are pivotally and rotatably con- 7 nected to ramp 10 by universal joint 22 (see FIGURE 5).

Pontoons 20 are parallel to each other and joined together by hollow U shaped tubular crossmembers 24 welded therebetween so as to define buoyant ramp means. (see FIGURE 7 also). The portions 21 of pontoons 20, nearest the barge are disposed at an obtuse vertical angle to the rest of the pontoons and such portions are not joined by crossmembers other than at universal joint 22. Cross members 24 have transverse inclined rollers 25, having rubber surfaces 26a mounted thereon (see FIGURE 7 also). The uppermost surfaces 26 of such rollers on alternate crossmembers are oppositely axially inclined (see also FIGURE 7).

The pontoons have hermetically sealed compartments 23 formed by water tight bulkheads of. which at least three, 23a, b and c are equipped with generally downwardly disposed blow-off pipes 28 which have remotely operated source of compressed air by lines 30. Sea cocks29 are connected to a source of valve operating gas pressure by line 31 which is connected to an external source of fluid pressure through pressure regulator 31a. All gas pressure lines are connected through central control panel 32. Remote control pressure line valves 33 for sea cocks 29 and three way valves 34for operating ga pressure lines 30 are located in panel 32. Gas lines 30 and 31 are contained and protected by headers 35 which together with valves 33 and 34 form control panel 32 which is mounted on a normally horizontal section 21 of pontoons 2t Semi-elliptical tubular skid members 40 are welded to the lower ends of pontoons 20 (see FIGURE 4.)

Referring to FIGURE 4, pontoon 20 is shown cutaway revealing transverse air tight bulkheads 27 forming the compartments. Air lines 30 from control panel 32 are connected to compartments 23a, band c and instrument air lines 31 are connected to sea cocks 29 controlling the flow throughblow-off pipes 28, respectively.

Referring now to FIGURE 6, the sea cook 29 comprises a substantially cylindrical housing 42 having an outside port 44 and compartment port 46 connected to blow-oft pipe 28, in the wall thereof. Operating piston 48 is slidably disposed in cylinder bore 50 and attached thereto is rod 52 slidably disposed in guide 54 which has passages 55 I therethrough. Ball check member 56 is disposed in chamber 58, seats on annular ring 60 and is biased to close by spring 62 which is seated in'well'63 and which spring surrounds guide plug 65 Whichalso seats in well 63. Instrument gas pressure is received through instrument fluid pressure port 64 in cylinder head 43.

In operating, the pipe 11 is assembled on barge 12. As the barge moves forward, the pipe slides rearwardly and downwardly over the rollers of rockable shoes 14 which support and assume positions roughly parallel to the pipe passing thereover. As the pipe passes to the rear over the shoes,lit passes headers 35, over the end of ramp 16 and universal joint 22, over normally horizontal sections 21 and between pontoons 20. After it leaves the barge, the pipe is next supported by rollers 25 mounted on crossmembers 24 which center and support the pipe below and between the pontoons 20.

The pipe continues downwardly between the pontoons and is laid in permanent position on the bottom 36. The vertical angular displacement between the buoyant cradle and barge is determined by the weight of the pipe, the total buoyancy of the cradle, and the location of the center of buoyancy of thepontoons. The buoyant factors of the pontoons are remotely controlled by flooding or evacuating selected compartments 23a, b and c. The,

other compartments are sealed voids which are sufiicient in number and buoyancy to give the shoe cradle a zero we1ght under water when all active compartments are flooded. Buoyancy in a given active compartment is maintained by gas pressure introduced into the pontoons by the air lines 30 and the operation sea cocks 29 which controls the inlet or exhaust of Water in the compartment. Each of these operations are remotely controlled. Active compartments can be emptied by the use of instrument gas pressure to the sea cocks and the introducing of'sufficient operation gas pressure through lines 30 to blow out the water throughblow-off pipes 28 and sea cocks 29. In deeper water, where greater cradle angularity is desired,selected active compartments may be flooded to lessen total buoyancy and move the center of buoyancy towards the barge. In accomplishing this, air pressure in line 30 is shut off by means of three way. valves 34 at the panel 32 and at the same time air pressure lines 30 are used to exhaust air from the compartments while the sea cocks 29 are opened by instrument gas pressure in lines 31 controlled by valves 33 in panel 32 to allow water to enter the compartments through the blow-oft" pipes 28. Variations of such procedures may be followed to obtain any cradle buoyancy, and inclination, desired.

Specifically, sea cocks 29 are opened by introducing fluid pressure into cylinder bore 50 through port 64, which drives piston 48 and rod 52 toward ball member 56. Rod 52 contacts ball 56, pushing it off its seat 60 against bias spring 62 which is guided by plug 65 sliding into well 63 and which operation allows Water to enter through outside port 44, pass through annular seat 60 and into the compartment port 46 when the compartments are being flooded. When such operation is accomplished, operating pressure is relieved in bore 50, bias spring 60 pushes ball 56 back on seat 60 which in turn urges rod 52 and piston 48 toward rest position. The fluid pressure in the compartment also acts on the reverse face of piston 48 through passages 55. The same operation, in conjunction with the use of operating fluid pressure, blowsout or empties the compartments.

It is possible, if desired and where water depth permits, to allow semi-elliptical skids 40 to drag the bottom whereby the pipe is continuously supported from point of assembly to permit disposition on the bottom.

While a preferred embodiment of the invention has been shown and described, many modifications thereof may be made by a person skilled in the art without department from the spirit of the invention and it is desired to protect by Letters Patent all of the inventions falling with the scope of the following claims:

We claim:

1. An apparatus for laying elongate, flexible means on a submerged surface, said apparatus comprising:

floating vessel means; elongate, unitary ramp means; connecting means pivotably attaching said elongate ramp means to said floating vessel means such that said ramp means extends longitudinally away from said floating vessel means and is pivotable about a generally horizontal axis; said ramp means having at least a portion submerged and inclined relative to a horizontal plane, and a lower end terminating above said submerged surface;

first support means on said floating vessel means for supporting a portion of elongate, flexible means for axial, slidable movement therealong with the axis of said portion extending in a generally straight line;

second support means on said floating vessel means for supporting a portion of elongate, flexible means for axial, slidable movement therealong with the axis of said portion being curved; third support means carried by said ramp means for supporting a portion of elongate, flexible means for axial, slidable movement therealong with the axis of said portion extending in a generally straight line;

said ramp means including a plurality of mutually independent compartment means displaced longitudinally therealong;

first buoyancy adjusting means for selectively and independently supplying ballast to each of a plurality of said compartment means;

second buoyancy adjusting means for selectively and independently removing ballast from each of a plurality of said compartment means;

control means for operating said first and second buoyancy adjusting means so as to adjust the inclination of at least a submerged and inclined portion of said ramp means to a predetermined position, to maintain said position, and to maintain the lower end of said ramp means at a predetermined elevation above said submerged surface; and

said control means including separate controls for first and second buoyancy adjusting means for each of a plurality of longitudinally displaced compartment means whereby an upwardly directed buoyant force exerted by each of said plurality of compartment means may be selectively and independently varied. 2. In combination: elongate, flexible conduit means;

6 floating vessel means; elongate, unitary ramp means; connecting means pivotably attaching said elongate ramp means to said floating vessel means such that said ramp means extends longitudinally away from said floating vessel means and is pivota'ble about a generally horizontal axis; said ramp means having at least a portion submerged and inclined relative to a horizontal plane, and a lower end terminating above said submerged surface; first support means on said floating vessel for supporting a portion of said elongate, flexible means for axial slidable movement therealong with the axis of said portion extending in a generally straight line; second, vertically adjustable, suppport means on said floating vessel means for supporting a portion of said elongate, flexible means for axial, slidable movement therealong with the axis of said portion being curved; third support means carried by said ramp means for supporting a portion of said elongate, flexible means for axial, slidable movement therealong with the axis of said portion extendingin a generally straight line; said elongate flexible conduit means being disposed such that a portion is supported for axial, slidable movement on said first supporting means, a portion is supported on said second supporting means for axial slidable movement, a portion is supported on said third support means for axial slidable movement, a portion thereof is unsupported between the lower end of said ramp means and said submerged surface, and a portion lies on said submerged surface; said ramp means including a plurality of mutually independent compartment means displaced longitudinally therealong; first buoyancy adjusting means for selectively and independently supplying ballast to each of a plurality of said compartment means; second buoyancy adjusting means for selectively and independently removing ballast from each of a plurality of said compartment means; control means operable from said floating vessel means for operating said first and second buoyancy adjusting means so as to remotely adjust the inclination of at least said submerged and inclined portion of said ramp means to a predetermined position, maintain said position, and maintain the lower end of said ramp means at a predetermined elevation above said submerged surface; and said control means including separate controls for first and second longitudinally displaced buoyancy adjusting means for each of a plurality of compartment means whereby an upwardly directed buoyant force exerted by each of said plurality of compartment means may be selectively and independently varied. 3. A combination as described in claim 2: wherein an unsupported portion of said flexible conduit means extends between said second support means and said third support means; wherein said connecting means is disposed at an elevation beneath said second support means; wherein said ramp means terminates substantially at said connecting means; wherein said ramp means comprises a pair of generally parallel and tubular pontoons; wherein each compartment means comprises,

laterally adjacent and generally tubular wall portions of said pair of pontoons, longitudinally spaced wall means within each of said pontoons which cooperate with said pontoon wall portions to define closed chambers, and chamber connecting conduit means extending transversely between said pontoon wall portions and connecting the closed chambers of each of said pontoon portions in fluid communicating relat-ionship, said connecting conduit means extending beneath said third support means; said third support means being supported by said connecting conduit means of said ramp means and disposed at an elevation lower than the longitudinal axes of said pontoons; wherein said third support means slidably supports a portion of said elongate, flexible conduit means with the axis thereof disposed beneath and between the axes of laterally adjacent portions of said pair of pontoons; wherein said first and second support means each comprise a plurality of roller means; and wherein said second support means includes adjustable mounting means for at least some of the roller means thereof adapted to secure said roller means in selectively adjustable positions of elevation, and pivot means supporting at least some of said roller means for pivotable movement about a generally horizontal axis extending generally transversely of a median plane extending longitudinally of said flexible conduit means. 4. A combination as described in claim 3: wherein said third support means comprises an individual roller mounted on each connecting conduit means of said float means and having an axis of rotation inclined relative to a horizontal plane; wherein said rollers, in a direction extending longitudinally of said ramp means, are alternately inclined in generally opposite directions; and wherein said rollers are disposed on said connecting conduit means such that mid-portions of said rollers engage lower portions of said flexible conduit means. 5. A combination as described in claim 3: wherein each of said pontoons of said ram-p means has a substantially straight portion adjacent said connecting means which is inclined relative to another, substantially straight, and submerged portion of said pontoon. 6. A combination as described in claim 3: wherein said first buoyancy adjusting means comprises in association with each of said compartment means,

a first fluid line and means for supplying and withdrawing air from said compartment means through said first fluid line; and wherein said second buoyancy adjusting means comprises, in association with each of said compartment means,

a second fluid line, and a valve in said second fluid line, said valve comprising a water inlet, a resiliently biased check valve closing said water inlet, and fluid pressure operated means for opening said check valve, and means for supplying fluid pressure to said pressure operated means to cause said pressure operated means to open said check valve whereby said compartmentmeans may beflooded with water. 7. A combination as described in claim 3: wherein each of said pontoons of said ram-p means has a substantially straight portion adjacent said connecting means which is inclined relative to another, substantially straight, and submerged portion of said pontoon; wherein said first buoyancy adjusting means comprises, in association with each of said compartment means,

a first fluid line and 8 means for supplying and withdrawing air from said compartment means through said first fluid line; wherein said sec-0nd buoyancy adjusting means comprises, in association witheach of said compartment means,

a second fluid line, and

a valve in said second fluid line, said valve comwherein said third support means comprises an individual roller mounted on each connecting conduit means of said float means and having an axis of rotation inclined relative to a horizontal plane;

wherein said rollers, in a direction extending longitudinally of said ramp means, are alternately inclined in generally opposite directions; and

wherein said rollers are disposed on said connecting conduit means such that mid-portions of said rollers engage lower portions of said flexible conduit means.

8. A method of laying elongate, flexible means on a submerged surface, said method comprising:

buoyantly supporting a portion of elongate, flexible means on a vessel floating on a fluid body such that said portion is axially slidable;

buoyantly supporting another portion of said elongate,

flexible means with the axis thereof extending generally downwardly and outwardly from said vessel,

with said other portion being at least in part submerged beneath said fluid body and axially slidable; exerting longitudinally spaced, and selectively and independently variable buoyant lifting forces on said other portion of said elongate, flexible means, with said buoyant forces being generated within said fluid body and generally adjacent said other portion of said elongate flexible means; and selectively and independently adjusting said buoyant lifting forces from said vessel so as to obtain and maintain a predetermined positioning of said other portion of said elongate, flexible means with the axis thereof extending generally downwardly and outwardly from said vessel. 9. A method as described in claim 8: wherein said buoyant lifting forces are generated generally laterally of and oneach side of said other portion of said elongate, flexible means and transmitted to the underside of said other portion; and wherein said buoyant forces generated on laterally ad jacent, opposite sides of said other portion are balanced. 10.'A device for laying underwater pipelines comprismg:

means for slidingly engaging, supporting, and guiding a pipeline above the surface of the water, and a cradle, vertically pivotally attached to said means, extending first substantially horizontally outwardly and thence outwardly and downwardly from said means to a point below the surface of the water, said cradle comprising a pair of transversely connected fluid-tight tubular members, and means transversely dividing said tubular members into a plurality of fluid-tight compartments extending throughout substantially the full length of the cradle, means for controlling the vertical angular position of said cradle withrespect to the first named means, comprising means for selectively flooding and removing water from at least some of said compartments, control means on said floating vessel means for operatand ing said buoyancy adjusting means so as to adjust the means on said cradle for supporting a pipeline. orientation of at least a submerged portion of said 11. An apparatus for laying elongate, flexible means ramp means to a predetermined position and to mainon a submerged surface, said apparatus comprising: 5 tain said position;

elongate, flexible means; said control means including separate controls for each floating vessel means; of said plurality of longitudinally displaced comelongate, unitary ramp means; partment means whereby an upwardly directed buoyconnecting means pivotably attaching said elongate ant force exerted by each of said plurality of comramp means to said floating vessel means; 10 partment means may be selectively and independ said ramp means having at least a portion submerged, ently varied.

and extending generally downwardly and away from i fl ati vessel means; References Cited by the Examiner support means on said pivotably connected floating ves- UNITED STATES PATENTS sel means and ramp means supporting said elongate 15 flexible means for generally axial, slidable movement; 7 5 5 Mfifedew 7 9 said ramp means including a plurality of mutually i 2,735,270 11/1956 Collins 6l-72.3

dependent compartment means displaced longitu- 2,793,650 4/1957 KraCht 137209 dinally therealong; 2,910,835 11/ 1959 Timothy 61--72.3 buoyancy adjusting means for selectively and inde- 20 3,054,267 9/ 1963 Alcoln at al 61-465 pendently supplying ballast to each of a plurality of JACOB L NACKENOFF, Prmmry Examiner. said longitudinally displaced compartment means and removing ballast from each of said plurality of said CHARLES OCONNELL compartment means; and J. SHAPIRO, Assistant Examiner. 

1. AN APPARATUS FOR LAYING ELONGATED, FLEXIBLE MEANS ON A SUBMERGED SURFACE, SAID APPARATUS COMPRISING: FLOATING VESSEL MEANS; ELONGATED, UNITARY RAMP MEANS; CONNECTING MEANS PIVOTABLY ATTACHING SAID ELONGATE RAMP MEANS TO SAID FLOATING VESSEL MEANS SUCH THAT SAID RAMP MEANS EXTENDS LONGITUDINALLY AWAY FROM SAID FLOATING VESSEL MEANS AND IS PIVOTABLE ABOUT A GENERALLY HORIZONTAL AXIS; SAID RAMP MEANS HAVING AT LEAST A PORTION SUBMERGED AND INCLINED RELATIVE TO A HORIZONTAL PLANE, AND A LOWER END TERMINATING ABOVE SAID SUBMERGED SURFACE; FIRST SUPPORT MEANS ON SAID FLOATING VESSEL MEANS FOR SUPPORTING A PORTION OF ELONGATE, FLEXIBLE MEANS FOR AXIAL, SLIDABLE MOVEMENT THEREALONG WITH THE AXIS OF SAID PORTION EXTENDING IN A GENERALLY STRAIGHT LINE; SECOND SUPPORT MEANS ON SAID FLOATING VESSEL MEANS FOR SUPPORTING A PORTION OF ELONGATE, FLEXIBLE MEANS FOR AXIAL, SLIDABLE MOVEMENT THEREALONG WITH THE AXIS OF SAID PORTION BEING CURVED; THIRD SUPPORT MEANS CARRIED BY SAID RAMP MEANS FOR SUPPORTING A PORTION OF ELONGATE, FLEXIBLE MEANS FOR AXIAL, SLIDABLE MOVEMENT THEREALONG WITH THE AXIS OF SAID PORTION EXTENDING IN A GENERALLY STRAIGHT LINE; SAID RAMP MEANS INCLUDING A PLURALITY OF MUTUALLY INDEPENDENT COMPARTMENT MEANS DISPLACED LONGITUDINALLY THEREALONG; FIRST BUOYANCY ADJUSTING MEANS FOR SELECTIVELY AND INDEPENDENTLY SUPPLYING BALLAST TO EACH OF A PLURALITY OF SAID COMPARTMENT MEANS; SECOND BUOYANCY ADJUSTING MEANS FOR SELECTIVELY AND INDEPENDENTLY REMOVING BALLAST FROM EACH OF A PLURALITY OF SAID COMPARTMENT MEANS; CONTROL MEANS FOR OPERATING SAID FIRST AND SECOND BUOYANCY ADJUSTING MEANS SO AS TO ADJUST THE INCLINATION OF AT LEAST A SUBMERGED AND INCLINED PORTION OF SAID RAMP MEANS TO A PREDETERMINED POSITION, TO MAINTAIN SAID POSITION, AND TO MAINTAIN THE LOWER END OF SAID RAMP MEANS AT A PREDETERMINED ELEVATION ABOVE SAID SUBMERGED SURFACE; AND SAID CONTROL MEANS INCLUDING SEPARATE CONTROLS FOR FIRST AND SECOND BUOYANCY ADJUSTING MEANS FOR EACH OF A PLURALITY OF LONGITUDINALLY DISPLACED COMPARTMENT MEANS WHEREBY AN UPWARDLY DIRECTED BUOYANT FORCE EXERTED BY EACH OF SAID PLURALITY OF COMPARTMENT MEANS MAY BE SELECTIVELY AND INDEPENDENTLY VARIED. 